Cosa
Cosa sits on a hill 113 meters above the Tyrrhenian Sea, a ruined Roman city near what is now Ansedonia in southwestern Tuscany. In AD 417, a traveler named Rutilius Claudius Namatianus passed by and recorded what he found: a deserted site in ruins, its population apparently driven away by a plague of mice. It is a strange epitaph for a place that had once been a strategic outpost of Roman power, a busy trading port, and a laboratory of Roman civic design.
How did Cosa rise from a patch of confiscated Etruscan land to become one of the most revealing windows into Roman colonial life? What do its walls, temples, fish tanks, and wine jars tell us about the ambitions of the Roman Republic? And why did this town keep emptying out, filling back up, and emptying again across nearly a thousand years of occupation?
In 273 BC, Rome planted Cosa on land taken from the defeated Etruscans. The Ager Cosanus, as this territory was called, was fresh conquest, and the new colony was designed to hold it. Cosa's position was not accidental. Scholars have argued that the city was founded specifically to give Rome a defensible port close to the timber and supplies of the Tuscan hinterland, resources that would soon be needed to build the fleets Rome was preparing for its confrontations with Carthage.
The road connecting Cosa to Rome, the Via Aurelia, was in place by about 241 BC. That link mattered. Without it, a hilltop colony 140 kilometers from the capital would have been an island. With it, Cosa became a node in a growing network of Roman authority along the Tyrrhenian coast.
The Etruscan presence at the site was not entirely erased. A town the Etruscans called Cusi or Cosia may have stood where Orbetello is today, and a stretch of polygonal masonry at Orbetello's lagoon may be structurally related to the walls Rome later built at Cosa itself. The Romans absorbed and built on what they found, as they so often did.
The city wall of Cosa was laid out at the moment of the colony's founding in 273 BC. It ran for 1.5 kilometers, built in polygonal masonry of what scholars classify as Lugli's third type, and it was reinforced by eighteen interval towers, all but one rectangular, the exception being round. Three gates pierced the circuit, each taking its name from the direction it faced: the northwest gate toward Florence, the northeast gate toward Rome, the southeast gate toward the sea.
Every gate followed the same defensive logic. Twin barriers, one flush with the outer wall and one set back toward the interior, created a trap between them for any attacker who broke through the first. The citadel, or Arx, had its own independent wall with a postern at the western corner, later closed when Byzantine forces refortified the hill in the early medieval period.
Inside the walls, Cosa was laid out on an orthogonal grid adapted to the uneven topography of the hill. The forum occupied a saddle between two heights, and the sacred area on the Arx was connected to it by a broad street. Recent excavation work has suggested that the original plan provided for around 248 houses, with 20 set aside for the decurions, the governing class, each one double the size of an ordinary citizen's home. That doubling was not subtle. The larger houses clustered around the forum and the main processional streets, visible to anyone walking through the center of town.
The Arx, positioned at the highest and southernmost point of the colony, constituted about one-twentieth of the total townsite. It was where the gods lived. Frank E. Brown, the archaeologist who led the first serious excavations of the citadel beginning in 1948, found a pit he believed was connected to the founding rituals performed at Cosa in 273 BC. Whether that is correct remains contested, but the pit's presence points to a moment of deliberate ceremony at the colony's birth.
The grandest structure on the Arx was the Capitolium, a three-cella temple built in the 2nd century BC. As far as scholars can determine, it is the only Capitolium known to have been built in a Latin colony, a direct echo of the great Temple of Jupiter, Juno, and Minerva on Rome's own Capitoline Hill. The Cosa Capitolium was oriented toward the northeast and rose from a high podium, its steps running across the entire facade, visible from the forum below via the Via Sacra. It would have been visible for miles at sea.
Dating to the late 3rd century BC, a smaller building called Temple D stood opposite the Capitolium's forecourt. It has been tentatively identified as a sanctuary to Mater Matuta, a Roman-Italic goddess, though scholars treat that identification as speculative. A third temple on the Arx, destroyed by fire in antiquity and never rebuilt, left only fragments of its terracotta decoration, including antefixes bearing busts of Minerva and Hercules. Their parentage, both being offspring of Jupiter, has led to the suggestion that the temple belonged to that god, but the question remains open.
One-tenth of Cosa's entire townsite was given over to the forum. The four cisterns within it held approximately 988,000 liters of water, and a reservoir at the forum's western corner added another 750,000 liters. That reservoir pre-dated the Roman colony itself, suggesting that the site had infrastructure worth inheriting.
The Comitium, the assembly space, was built before the First Punic War, and its amphitheatric steps were calculated for standing, not sitting: each step measured about 33 centimeters by 40 centimeters, too narrow for comfort as a seat. Approximately 600 people could stand on those steps. The arrangement echoes what Roman archaeologists have documented at Rome itself, where the Comitium led up to the Curia in a similar configuration.
The Curia at Cosa, originally a two-story wooden structure on a stone base, was rebuilt repeatedly over the centuries. Its most significant expansion came around 173 BC, when a larger, three-hall building replaced the earlier one. Scholars identify that moment with the arrival of a second wave of colonists who needed more institutional space. The Basilica followed after the Curia was in its third form, and Temple B, dateable to around 175-150 BC, was seriously damaged by a collapsing wall before being rebuilt to preserve its older sacred core within a new shell.
A sack of the city in 70 BC ended much of this activity. Several of the forum's Atrium Buildings were never rebuilt. An earthquake in the 50s AD set off another round of reconstruction, and it was during that period that a man named Lucius Titinius Glaucus Lucretianus took over what had been a private house and directed the conversion of the old Basilica into an odeum.
On the south side of the forum stood a house 16 meters wide, built around 170 BC on the standard Roman atrium plan, with a striking resemblance to the House of Sallust at Pompeii. Excavated and restored between 1995 and 1999 and published in full by E. Fentress in 2004, the House of Diana gives the most detailed picture of elite domestic life at Cosa.
Two tabernae, or shops, faced the forum from the building's front. The rear rooms of one appear to have been used for wine storage; the other for food. Between them, a narrow entrance passage, the fauces, led into an atrium open to the sky at the center, with a pool to catch rainwater. Side rooms opened off the atrium, and at the back were the kitchen, the reception room, and the dining room, beyond which lay a garden probably used for growing vegetables, as a large compost heap nearby suggests.
Destroyed around 70 BC, the house was entirely rebuilt in the Augustan period, acquiring fine frescoes and mosaics in the process. The garden became ornamental, connected to a newly opened dining room through a colonnaded loggia for summer meals. Two eastern cubicula were joined into a single room for winter use.
In the 50s AD, the house became associated with Lucius Titinius Glaucus Lucretianus, who added a small temple to Diana in its garden. Among the objects found there was a fourth-century BC head of a woman carved in Greek marble. The house was abandoned no later than the end of the 1st century AD, and by the 3rd century the space it had occupied was turned into a granary.
Below the city, at the foot of the hill to the southeast, lay a harbor that scholars now recognize as the earliest Roman port known to have survived. Founded likely in 273 BC alongside the colony itself, it remained in use into the 3rd century AD. In the ancient world it offered the best anchorage on the Tyrrhenian coast between Gaeta to the south and La Spezia to the north.
Frank E. Brown first surveyed the port in 1951. Later excavators, working under conditions that required new technical invention, benefited from a water jet prober designed by Colonel John D. Lewis to locate structures buried in harbor sediment, along with a sheet-steel cylinder construction that allowed underwater stratification to be recorded for the first time. Those methods fixed ancient harbor levels at between one meter and one meter eighty below the current sea floor.
Five large masonry piers survive in the outer harbor, built from tufa and mortared rubblework packed with amphora sherds of Dressel Type I, pointing to a construction date in the 2nd or 1st centuries BC. Tufa and pozzolana concrete, resistant to salt water, formed the foundation of the harbor's hydraulic engineering. This represents the earliest known use of that concrete formula in a marine setting.
About 250 meters behind the port, excavations found the earliest known commercial fishery, complete with two long fish tanks, a freshwater spring housed in a Spring House on the western embankment, and channels that circulated water to control salinity and temperature. Fish sauce, or garum, was produced here, a commodity whose trade was considered more lucrative than most wines.
The wine trade was substantial in its own right. Fragments of transport amphorae from the beach and offshore areas of the harbor include the earliest pieces dating to the late 3rd century BC. Many were stamped with the mark of the Sestius family, identified as major wine exporters whose commercial reach extended into Gaul. The earliest Sestius amphorae at Cosa date to 175-150 BC. The sheer volume of these fragments has led scholars to conclude that Cosa's port was likely the main manufacturing and distribution point for the Sestius jars.
Malaria may have been the thread running through Cosa's intermittent occupation. Already in the early Empire, the Tuscan coast was reportedly hyperendemic with the disease, and the pattern of Cosa's habitation, prosperous for a generation or two, then depopulated, then slowly revived, fits a place where seasonal conditions kept driving people away.
An earthquake in 51 AD prompted reconstruction of the Republican Basilica as an Odeon, work attributed to Lucius Titinius Glaucus Lucretianus. By around 80 AD, however, the city appears to have been nearly deserted again. A revival under the emperor Caracalla brought new construction: a portico around the forum concealing two large granaries, a restored odeum, a Mithraeum in the basement of the Curia, and a sanctuary to Liber at the southeastern end of the Forum. By the middle of that same century, occupation had ceased again, except for visitors to the sanctuary.
By the 4th century only that sanctuary of Liber was still periodically visited. Rutilius Claudius Namatianus saw ruins and perhaps a mouse infestation in AD 417. Pottery from the early 6th century attests to some activity in those ruins, and the remains of a church have been found built onto the old Basilica. The Arx was occupied briefly by a fortified farm that later became a Byzantine outpost, abandoned in the late 6th or early 7th century.
Medieval occupation returned gradually. A 9th-century date is suggested by frescoes at the Roman abbey of S. Anastasio alle Tre Fontane, which record the capture of the site by Charlemagne and Pope Leo III, though no physical evidence of occupation from the 8th through 10th centuries has been recovered. By the 11th century, a church had been built over a forum-facing temple and a small settlement had taken shape on the Eastern Height, ringed by a double bank and ditch. A tower built in the 12th century had a cistern on two sides; graffiti on that cistern's plaster lining includes one inscription dated 1211, the record of a prisoner. The castle belonged to the Aldobrandeschi family in 1269 and was razed by the Sienese army in 1329, on the stated grounds that it harbored bandits. After that destruction, the site remained deserted.
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Common questions
When was Cosa founded and why did the Romans build it?
Cosa was founded by Rome as a Latin colony in 273 BC on land confiscated from the defeated Etruscans. The Romans established it on the Ager Cosanus to consolidate control over the region and secure a strategically defensible port close to Tuscan timber supplies needed for building Rome's early naval fleets.
Who excavated Cosa and when did the excavations take place?
The major excavations at Cosa were conducted under the auspices of the American Academy in Rome, initially directed by archaeologist Frank Edward Brown in campaigns from 1948 to 1954 and 1965 to 1972. In the 1990s, Elizabeth Fentress led a follow-up campaign focused on the site's history between the imperial period and the Middle Ages. From 2005 to 2012, the Universities of Granada and Barcelona excavated a domus, and from 2013 Florida State University has excavated a bath building.
What is the Capitolium at Cosa and why is it significant?
The Capitolium at Cosa is a triple-cella temple built in the 2nd century BC at the summit of the Arx, the city's sacred citadel. It is believed to be the only Capitolium known to have been constructed in a Latin colony, modeled after the 6th-century BC Temple of Jupiter, Juno, and Minerva in Rome. Situated high enough to be visible for miles at sea, it was likely built as an affirmation of Roman loyalty following the Second Punic War.
What is the earliest Roman harbor and where is it?
The port of Cosa, located below the ancient city on the Tyrrhenian coast of Tuscany, is identified as the earliest Roman harbor known thus far. It was likely founded alongside the colony in 273 BC and remained in use into the 3rd century AD. The port also preserves the earliest known commercial fishery and the earliest evidence for the use of tufo and pozzolana concrete in water.
Who were the Sestii and what was their connection to Cosa?
The Sestius family were major exporters of wine whose stamped amphorae have been found in large numbers at the port of Cosa, with the earliest examples dating to 175-150 BC and continuing into the 1st century BC. The abundance of Sestius amphora fragments at the harbor suggests that Cosa was the primary center for manufacturing and distributing these famous jars, with the family's trade network extending as far as Gaul.
Why was Cosa repeatedly abandoned throughout its history?
Scholars attribute the intermittent occupation of Cosa partly to hyperendemic malaria on the Tuscan coast, which may have made sustained habitation difficult from the early Empire onward. The city also suffered from the disruptions of the Roman Republican civil wars in the 60s BC, a major earthquake in 51 AD, and periodic economic decline. By AD 417, the traveler Rutilius Claudius Namatianus recorded that the site was deserted and in ruins, suggesting a plague of mice had driven away the last inhabitants.
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10 references cited across the entry
- 2bookAugustus to Nero: A Sourcebook on Roman History, 31 BC-AD 68David Braund et al. — Routledge — 27 June 2014
- 3newsCosa in the empire: the unmaking of a Roman town'Elizabeth Fentress — 1994
- 4bookCosa: The Making of a Roman TownFrank Edward Brown — University of Michigan Press — 1980
- 5bookCosa 5Elizabeth Fentress — University of Michigan Press — 2003
- 6inlineFSU Cosa Excavations
- 7bookRoman CitiesPierre Grimal et al. — Univ of Wisconsin Press — 1983
- 9bookUrbes ExtinctaeElizabeth Fentress et al. — 2012
- 10bookA Companion to the Archaeology of the Romman RepublicJane DeRose Evans — Wiley — 29 March 2013